Multimedia communications between two stations may use either wired or wireless communications networks. These wired networks may be either packet based, such as Ethernet, or circuit based networks such as asynchronous transfer mode (ATM). Such networks may exist in an office building or between office locations of the same company, for use by company employees. In the case of portable equipment such as a laptop computer, when the user is away from his own office, either within the company premises, or traveling, he may wish to make use of a wireless communication network to communicate with other devices, including devices on the wired company network. Similarly, it may be desirable under some circumstances even for stationary equipment such as the desktop computer to communicate over a wireless network with other devices.
In a wireless network, a high speed wired communications network (a backbone network) may communicate with a number of base stations, which in turn communicate with users of the network services by wireless connections. These networks may be based on ATM technology. Thus, a number of subscribers may be coupled by wireless communications to a base station, and the base station is in turn coupled through an ATM switch to the high speed backbone network. The subscribers may be either stationary or mobile, and in the case of mobile subscribers, it may be necessary for the subscriber to communicate with a different base station from time to time, as a subscriber enters and leaves areas serviced by various base stations. In a wired network using an ATM backbone network, the users may be wired directly to ATM switches.
In the case of desktop computers, wired and wireless communications are usually supported by an appropriate interface board or "bus adapter" (e.g., S-bus, Nubus, ISA, PCI, EISA, or the like) installed inside the casing or housing of the computer, with suitable connector elements, or plugs, for a given wired network, or a suitable antenna to communicate with a wireless network, emerging exteriorally of the casing or housing. However, in order to switch from a wired network to a wireless network, it may be necessary to terminate a connection, if communication is currently in progress. That is, typically the steps would be: shut down the computer, remove the existing interface board, install a new interface board appropriate to the network to be used, and often provide new software for supporting the new interface. Adding to the problem, high level application software normally requires reconfiguration in order to utilize the changes in the network configuration.
In the case of laptop computers, communications are often provided by a network interface card, such as a PCMCIA type interface card, which is a relatively small, approximately credit card-sized element that physically enters a slot in a side panel of the laptop housing. However, these various network interface cards, or PCMCIA type cards, are specific to either wired or wireless networks, such that a communication session must terminate, the laptop shut down, and the network interface card changed to communicate with a new network. Again, it may also be necessary to provide new software to support the new interface card upon changing cards in this fashion.
Thus, the prior art has generally required multiple interface cards that must be interchanged, or other special configurations of equipment to allow a user device to change from wired to wireless communications networks. Modular interface cards such as ATM boards allow for users to plug in different modules for different types of wired connections; however, the user must still remove the interface cards from the host computer to change the module. Multiple modules cannot be connected to one interface board, and all modules supported utilize a wired medium. Thus, automatic switching between wired and wireless mediums is not possible with this approach.